android - 无法从 CursorWindow (Android) 读取第 0 行、第 1 列

Question

我在 MySQLiteHelper.java 中的 onCreate() 方法中创建了一个类似 Players 的表:

String CREATE_PLAYERS_TABLE = "CREATE TABLE Players 
(id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT, password TEXT, score INTEGER)";

db.execSQL(CREATE_PLAYERS_TABLE);

我在同一个类中有一个更新方法，例如:

public int PlayerUpdate(Player PL) {

    // 1. get reference to writable DB
    SQLiteDatabase db = this.getWritableDatabase();

    // 2. create ContentValues to add key "column"/value
    ContentValues values = new ContentValues();
    values.put("name", PL.getName());
    values.put("password", PL.getPassword());
    values.put("score", PL.getScore());

    // 3. updating row
    int i = db.update(TABLE_Players, // table
            values, // column/value
            KEY_ID + " = ?", // selections
            new String[] { String.valueOf(PL.getId()) }); // selection args

    // 4. close
    db.close();

    return i;
}

当我调用函数将 score 变量更改为:

public void scoreUp() {
    helper.PlayerUpdate(new Player(player_name,player_password,player_score+5));
}
public void scoreDown() {
    helper.PlayerUpdate(new Player(player_name,player_password,player_score-5));
}

我收到如下 logcat 错误:

Failed to read row 0, column 1 from a CursorWindow which has 1 rows, 1 columns.
FATAL EXCEPTION: main
java.lang.IllegalStateException: Could not execute method of the activity
Caused by: java.lang.IllegalStateException: Couldn't read row 0, col 1 from CursorWindow.  
Make sure the Cursor is initialized correctly before accessing data from it.

谢谢。

已解决:

还有另一个查询导致了这个特定的异常，我发现了。

Answer 1

异常来自访问游标列，您发布的代码没有显示。

但是，列索引从 0 开始，因此要将第一列值作为字符串访问，请使用 getString(0) 而不是 getString(1)。